This paper presents an investigation on dynamic characteristics of Heunginjimun through both ambient vibration and impact hammer tests. Heunginjimun, treasure No. 1 in Seoul, Korea, is a traditional wooden structure. Ambient vibration test is performed and spectrum analysis of time history is carried out to identify dominant frequency contents of Heunginjimun. Impact hammer test is undertaken to find the natural frequency of Heunginjimun with frequency response functions and phase information. Test results show that natural frequencies are 1.lHz, l.5Hz, 3.2Hz and 4.2Hz in two principal axes. Natural frequencies obtained by the tests are used to find the lateral stiffness of Heunginjimun. Simple dynamic models for Heunginjimun are suggested based on the moment resistance from joint beams and the restoring force due to column rocking. Lateral stiffness is found with identified natural frequencies and simple dynamic models.

As a results of comparing with fire occurrences and gross national income(GNI), annual fire increasing rate has been 5.6%, and that of GNI has been 11% for the past 55 years. As GNI shows 5.4% higher than fire occurrences, economy growing rate is faster than that of fires. In addition, study has been done every 10 years from 1950's to 2000's. Fire occurrences increase twice as much annually and GNI increases above 3.3 times as much.